body {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 100vw;
    height: 100vh;
    background: #000;
  }
  div {
    width: 400px;
    height: 400px;
    position: relative;
    overflow: hidden;
    padding: 15px;
    &::after {
      content: '';
      position: absolute;
      display: block;
      width: 100%;
      height: 100%;
      left: 0;
      top: 0;
      z-index: -1;
      transform: scale(3);
      background: linear-gradient(to right, #f1c40f, white, #e67e22, #e74c3c, #9b59b6);
      transition: 2s;
    }
    aside {
      height: 100%;
      overflow: hidden;
    }
    &:hover::after {
      transform: scale(3) rotate(260deg);
    }
  }